Infinite Recursion in running `??Int` after Rubi is loaded.

[rocky]

Description

After Rubi is loaded, ??Int (or Information["Int", LongForm -> True] goes into an infinite recursion

In MatchQ:

     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 636, column 9
E:1 (4) Expression.rewrite_apply_eval_step.<locals>.eval_elements <class 'mathics.core.expression.Expression'>
         eval_elements() file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1270, column 17
E:2 (5) Expression.rewrite_apply_eval_step <class 'mathics.core.expression.Expression'>
         rewrite_apply_eval_step(MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1284, column 13
E:3 (7) Expression.evaluate <class 'mathics.core.expression.Expression'>
         evaluate(MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 660, column 36
E:4 (10) Expression.rewrite_apply_eval_step.<locals>.eval_elements <class 'mathics.core.expression.Expression'>
          eval_elements() file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1270, column 17
E:5 (11) Expression.rewrite_apply_eval_step <class 'mathics.core.expression.Expression'>
          rewrite_apply_eval_step(Not[MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1284, column 13
E:6 (13) Expression.evaluate <class 'mathics.core.expression.Expression'>
          evaluate(Function[Not[MatchQ[#1, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]]]][_],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 660, column 36

How to Reproduce and Output Given

Git clone Rubi from GitHub and cd into the project root. Then.

$ mathics3 --post-mortem --full-form

Mathics3 10.0.2dev0
Running on linux CPython 3.14.6 (main, Jul 11 2026, 11:12:13) [GCC 13.3.0]
using SymPy 1.14.0, mpmath 1.3.0, numpy 2.5.1, cython 3.2.8, scipy 1.18.0, skimage 0.26.0

Copyright (C) 2011-2026 The Mathics3 Team.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions.
See the documentation for the full license.

Quit by evaluating Quit[] or by pressing CONTROL-D.

In[1]:= << Rubi.m

In[2]:= LoadModule["pymathics.trepan"]
System`LoadModule["pymathics.trepan"]
Out[2]= "pymathics.trepan"

In[3]:= $RecursionLimit = 20;
System`CompoundExpression[System`Set[System`$RecursionLimit, 20], System`Null]

In[4]:= TraceEvaluation[??Int]

In[4]:= TraceEvaluation[??Int]
System`TraceEvaluation[System`Information["Int", System`Rule[System`LongForm, System`True]]]
  Evaluating: Information["Int", LongForm -> True]
    Evaluating: LongForm -> True
    Returning : LongForm -> True -> LongForm -> True
  Returning : Information["Int", LongForm -> True] -> Information["Int", LongForm -> True]

(/tmp/Mathics3/mathics-core/mathics/core/evaluation.py:571:17 @234): inc_recursion_depth
-- 571                 self.error("$RecursionLimit", "reclim", limit)
(trepan3k) load trepan3k_mathics3
loaded command: "mabort"
loaded command: "mathics3"
loaded command: "mbacktrace"
...
(trepan3k) pe expr
_

(trepan3k) mbt
##0 inc_recursion_depth(self=<mathics.core.evaluation.Evaluation object at 0x76758a6e9c70>)
     file '/tmp/Mathics3/mathics-core/mathics/core/evaluation.py' at line 571, column 17
##1 evaluate(_,
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 636, column 9
->2 wrapper(expr=<Expression: <Symbol: System`Blank>[]>)
     file '/tmp/Mathics3/mathics-core/mathics/eval/tracing.py' at line 174, column 22
##3 eval_range(indices=range(0, 2))
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1236, column 41
##4 eval_elements() file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1270, column 17
##5 rewrite_apply_eval_step(MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1284, column 13
##6 wrapper(expr=<Expression: <Symbol: System`MatchQ>[<Expression: <Symbol: System`Blank>[]>, <Expression: <Sym...)
     file '/tmp/Mathics3/mathics-core/mathics/eval/tracing.py' at line 174, column 22
##7 evaluate(MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 660, column 36
##8 wrapper(expr=<Expression: <Symbol: System`MatchQ>[<Expression: <Symbol: System`Blank>[]>, <Expression: <Sym...)
     file '/tmp/Mathics3/mathics-core/mathics/eval/tracing.py' at line 174, column 22
##9 eval_range(indices=range(0, 1))
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1236, column 41
##10 eval_elements() file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1270, column 17
##11 rewrite_apply_eval_step(Not[MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1284, column 13
##12 wrapper(expr=<Expression: <Symbol: System`Not>[<Expression: <Symbol: System`MatchQ>[<Expression: <Symbol: S...)
     file '/tmp/Mathics3/mathics-core/mathics/eval/tracing.py' at line 174, column 22
##13 evaluate(Function[Not[MatchQ[#1, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]]]][_],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 660, column 36
##14 wrapper(expr=<Expression: <Expression: <Symbol: System`Function>[<Expression: <Symbol: System`Not>[<Express...)
     file '/tmp/Mathics3/mathics-core/mathics/eval/tracing.py' at line 174, column 22
##15 yield_match(vars_2={'System`pattern': <Expression: <Symbol: System`Blank>[]>}, rest=None)
     file '/tmp/Mathics3/mathics-core/mathics/builtin/patterns/restrictions.py' at line 361, column 30
##16 match(_,
	expression=<Expression: <Symbol: System`Blank>[]>, pattern_context={'yield_func': <function PatternT...)
     file '/tmp/Mathics3/mathics-core/mathics/builtin/patterns/basic.py' at line 111, column 9
##17 match(pattern:_,
	expression=<Expression: <Symbol: System`Blank>[]>, pattern_context={'yield_func': <function PatternT...)
     file '/tmp/Mathics3/mathics-core/mathics/builtin/patterns/composite.py' at line 504, column 17
##18 match(PatternTest[pattern:_, Function[Not[MatchQ[Slot[], Alternatives[_Blank, _BlankSequence, _BlankNullSe...),
	expression=<Expression: <Symbol: System`Blank>[]>, pattern_context={'yield_func': <function BasePatt...)
     file '/tmp/Mathics3/mathics-core/mathics/builtin/patterns/restrictions.py' at line 369, column 9
##19 does_match(PatternTest[pattern:_, Function[Not[MatchQ[Slot[], Alternatives[_Blank, _BlankSequence, _BlankNullSe...),
	expression=<Expression: <Symbol: System`Blank>[]>, pattern_context={'evaluation': <mathics.core.eval...)
     file '/tmp/Mathics3/mathics-core/mathics/core/pattern/base.py' at line 306, column 13
##20 yield_choice(pre_vars={})
     file '/tmp/Mathics3/mathics-core/mathics/core/pattern/ordered.py' at line 74, column 28
##21 get_pre_choices_with_order(pat=<ExpressionPattern: System`Verbatim[System`Pattern][System`Pattern[System`symbol, System`Blank[...)
     file '/tmp/Mathics3/mathics-core/mathics/core/pattern/ordered.py' at line 237, column 5
##22 yield_head(head_vars={}, _=None)
     file '/tmp/Mathics3/mathics-core/mathics/core/pattern/ordered.py' at line 127, column 13
##23 match(<mathics.builtin.patterns.composite.Verbatim object at 0x767581fc9550>,
	expression=<Symbol: System`Pattern>, pattern_context={'yield_func': <function basic_match_expression...)
     file '/tmp/Mathics3/mathics-core/mathics/builtin/patterns/composite.py' at line 742, column 13
##24 basic_match_expression(<mathics.builtin.patterns.composite.Verbatim object at 0x767581fc9550>[symbol:_, PatternTest[pattern...),
	expression=<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`Private`B>, <Expression: <Symbol: Sys...)
     file '/tmp/Mathics3/mathics-core/mathics/core/pattern/ordered.py' at line 143, column 5
##25 match(<mathics.builtin.patterns.composite.Verbatim object at 0x767581fc9550>[symbol:_, PatternTest[pattern...),
	expression=<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`Private`B>, <Expression: <Symbol: Sys...)
     file '/tmp/Mathics3/mathics-core/mathics/core/pattern/ordered.py' at line 390, column 21
##26 match(<mathics.builtin.patterns.composite.Verbatim object at 0x76758ccaf520>[symbol:_, PatternTest[pattern...),
	expression=<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`Private`B>, <Expression: <Symbol: Sys...)
     file '/tmp/Mathics3/mathics-core/mathics/core/pattern/deferred.py' at line 75, column 16
##27 apply(self=<Rule: <DeferredExpressionPattern: System`Verbatim[System`Pattern][System`Pattern[System`symbo...)
     file '/tmp/Mathics3/mathics-core/mathics/core/rules.py' at line 207, column 13
##28 format_expr(expr=<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`Private`B>, <Expression: <Symbol: System`B...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 136, column 26
##29 do_format_element(element=<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`Private`B>, <Expression: <Symbol: Syste...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 141, column 21
##30 do_format_expression(element=<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`Private`B>, <Expression: <Symbol: Syste...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##31 <genexpr>(.0=<tuple_iterator object at 0x76757e328460>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##32 do_format_element(element=<Expression: <Symbol: System`Optional>[<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##33 do_format_expression(element=<Expression: <Symbol: System`Optional>[<Expression: <Symbol: System`Pattern>[<Symbol: Rubi`...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##34 <genexpr>(.0=<tuple_iterator object at 0x76758954e7a0>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##35 do_format_element(element=<ListExpression: (<Expression: ...`Blank>[]>]>]>, <Expression: ...em`Blank>[]>]>)>, evaluat...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##36 <genexpr>(.0=<tuple_iterator object at 0x76758954eb60>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##37 do_format_element(element=<Expression: <Symbol: System`Infix>[<ListExpression: (<Expression: ...`Blank>[]>]>]>, <Expr...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##38 do_format_expression(element=<Expression: <Symbol: System`Infix>[<ListExpression: (<Expression: ...`Blank>[]>]>]>, <Expr...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##39 <genexpr>(.0=<tuple_iterator object at 0x76758954fc70>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##40 do_format_element(element=<Expression: <Symbol: System`HoldForm>[<Expression: <Symbol: System`Infix>[<ListExpression:...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##41 do_format_expression(element=<Expression: <Symbol: System`HoldForm>[<Expression: <Symbol: System`Infix>[<ListExpression:...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##42 do_format_element(element=<Expression: <Symbol: System`Times>[<Expression: <Symbol: System`Optional>[<Expression: <Sy...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 144, column 22
##43 do_format_expression(element=<Expression: <Symbol: System`Times>[<Expression: <Symbol: System`Optional>[<Expression: <Sy...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##44 <genexpr>(.0=<tuple_iterator object at 0x76757ebdc8e0>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##45 do_format_element(element=<Expression: <Symbol: System`HoldForm>[<Expression: <Symbol: System`Times>[<Expression: <Sy...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##46 do_format_expression(element=<Expression: <Symbol: System`HoldForm>[<Expression: <Symbol: System`Times>[<Expression: <Sy...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##47 <genexpr>(.0=<tuple_iterator object at 0x76757ebdf130>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##48 do_format_element(element=<ListExpression: (<Expression: ...lank>[]>]>]>]>, <Expression: ...lank>[]>]>]>]>, <Expressi...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##49 <genexpr>(.0=<tuple_iterator object at 0x76757ebde140>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##50 do_format_element(element=<Expression: <Symbol: System`Infix>[<ListExpression: (<Expression: ...lank>[]>]>]>]>, <Expr...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##51 do_format_expression(element=<Expression: <Symbol: System`Infix>[<ListExpression: (<Expression: ...lank>[]>]>]>]>, <Expr...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##52 do_format_element(element=<Expression: <Symbol: System`Plus>[<Expression: <Symbol: System`Optional>[<Expression: <Sym...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 144, column 22
##53 do_format_expression(element=<Expression: <Symbol: System`Plus>[<Expression: <Symbol: System`Optional>[<Expression: <Sym...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##54 <genexpr>(.0=<tuple_iterator object at 0x76757ebdc430>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##55 do_format_element(element=<ListExpression: (<Expression: ...`Blank>[]>]>]>, <Expression: ...eger: 2>]>]>]>, <Expressi...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##56 <genexpr>(.0=<tuple_iterator object at 0x76757ebdd840>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##57 do_format_element(element=<Expression: <Symbol: System`Infix>[<ListExpression: (<Expression: ...`Blank>[]>]>]>, <Expr...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##58 do_format_expression(element=<Expression: <Symbol: System`Infix>[<ListExpression: (<Expression: ...`Blank>[]>]>]>, <Expr...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##59 <genexpr>(.0=<tuple_iterator object at 0x76757ebddd80>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##60 do_format_element(element=<Expression: <Symbol: System`HoldForm>[<Expression: <Symbol: System`Infix>[<ListExpression:...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##61 do_format_expression(element=<Expression: <Symbol: System`HoldForm>[<Expression: <Symbol: System`Infix>[<ListExpression:...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##62 do_format_element(element=<Expression: <Symbol: System`Times>[<Expression: <Symbol: System`Optional>[<Expression: <Sy...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 144, column 22
##63 do_format_expression(element=<Expression: <Symbol: System`Times>[<Expression: <Symbol: System`Optional>[<Expression: <Sy...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##64 <genexpr>(.0=<tuple_iterator object at 0x76757ebdfa60>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##65 do_format_element(element=<Expression: <Symbol: Rubi`Int>[<Expression: <Symbol: System`Times>[<Expression: <Symbol: S...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##66 do_format_expression(element=<Expression: <Symbol: Rubi`Int>[<Expression: <Symbol: System`Times>[<Expression: <Symbol: S...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##67 <genexpr>(.0=<tuple_iterator object at 0x76757ebdc9a0>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##68 do_format_element(element=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: Rubi`Int>[<Expression: <Sym...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##69 do_format_expression(element=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: Rubi`Int>[<Expression: <Sym...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##70 <genexpr>(.0=<tuple_iterator object at 0x76757ebdd540>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##71 do_format_element(element=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: System`HoldPattern>[<Expres...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##72 do_format_expression(element=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: System`HoldPattern>[<Expres...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##73 <genexpr>(.0=<tuple_iterator object at 0x76757ebdc6a0>)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 173, column 21
##74 do_format_element(element=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: System`HoldPattern>[<Expres...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 171, column 28
##75 do_format_expression(element=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: System`HoldPattern>[<Expres...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 248, column 12
##76 do_format(element=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: System`HoldPattern>[<Expres...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/formatvalues.py' at line 54, column 14
##77 render_input_form(expr=<Expression: <Symbol: System`HoldPattern>[<Expression: <Symbol: System`HoldPattern>[<Expressio...)
     file '/tmp/Mathics3/mathics-core/mathics/format/form/inputform.py' at line 74, column 32
##78 inputform(expr=<Expression: <Symbol: System`InputForm>[<Expression: <Symbol: System`HoldPattern>[<Expression:...)
     file '/tmp/Mathics3/mathics-core/mathics/format/form/outputform.py' at line 447, column 12
##79 render_output_form(expr=<Expression: <Symbol: System`InputForm>[<Expression: <Symbol: System`HoldPattern>[<Expression:...)
     file '/tmp/Mathics3/mathics-core/mathics/format/form/outputform.py' at line 282, column 18
##80 _infix_outputform_text(expr=<Expression: <Symbol: System`Infix>[<ListExpression: (<Expression: ...]>]>]>]>]>]>]>, <Express...)
     file '/tmp/Mathics3/mathics-core/mathics/format/form/outputform.py' at line 417, column 18
##81 render_output_form(expr=<Expression: <Symbol: System`HoldForm>[<Expression: <Symbol: System`HoldForm>[<Expression: <Sy...)
     file '/tmp/Mathics3/mathics-core/mathics/format/form/outputform.py' at line 282, column 18
##82 grid_render_output_form(expr=<Expression: <Symbol: System`Grid>[<ListExpression: (<String: "Int... <a> to <b>.">, <Expressi...)
     file '/tmp/Mathics3/mathics-core/mathics/format/form/outputform.py' at line 347, column 25
##83 render_output_form(expr=<Expression: <Symbol: System`Grid>[<ListExpression: (<String: "Int... <a> to <b>.">, <Expressi...)
     file '/tmp/Mathics3/mathics-core/mathics/format/form/outputform.py' at line 282, column 18
##84 eval_makeboxes_outputform(expr=<Expression: <Symbol: System`Information>[<String: "Int">, <Expression: <Symbol: System`Rule>[...)
     file '/tmp/Mathics3/mathics-core/mathics/builtin/forms/print.py' at line 261, column 27
##85 eval_generic_makeboxes(expr=<Expression: <Symbol: System`OutputForm>[<Expression: <Symbol: System`Information>[<String: "I...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/makeboxes.py' at line 268, column 20
##86 apply_makeboxes_rules(expr=<Expression: <Symbol: System`OutputForm>[<Expression: <Symbol: System`Information>[<String: "I...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/makeboxes.py' at line 166, column 12
##87 format_element(element=<Expression: <Symbol: System`Information>[<String: "Int">, <Expression: <Symbol: System`Rul...)
     file '/tmp/Mathics3/mathics-core/mathics/format/box/makeboxes.py' at line 346, column 18
##88 format_output(self=<mathics.core.evaluation.Evaluation object at 0x76758a6e9c70>, expr=<Expression: <Symbol: Syst...)
     file '/tmp/Mathics3/mathics-core/mathics/core/evaluation.py' at line 407, column 22
##89 evaluate() file '/tmp/Mathics3/mathics-core/mathics/core/evaluation.py' at line 271, column 24
##90 evaluate(self=<mathics.core.evaluation.Evaluation object at 0x76758a6e9c70>, query=<Expression: <Symbol: Sys...)
     file '/tmp/Mathics3/mathics-core/mathics/core/evaluation.py' at line 278, column 26
##91 interactive_eval_loop(shell=<mathics.repl.TerminalShell object at 0x76758c608d70>, full_form=True, strict_wl_output=False...)
     file '/tmp/Mathics3/mathics-core/mathics/repl.py' at line 378, column 22
##92 main() file '/tmp/Mathics3/mathics-core/mathics/__main__.py' at line 284, column 5
##93 <module> sys(Ellipsis)
     file '/home/rocky/.pyenv/versions/3.14.6/bin/mathics3' at line 6, column 14
(trepan3k) mbt -e
E:0 (1) Expression.evaluate <class 'mathics.core.expression.Expression'>
         evaluate(_,
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 636, column 9
E:1 (4) Expression.rewrite_apply_eval_step.<locals>.eval_elements <class 'mathics.core.expression.Expression'>
         eval_elements() file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1270, column 17
E:2 (5) Expression.rewrite_apply_eval_step <class 'mathics.core.expression.Expression'>
         rewrite_apply_eval_step(MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1284, column 13
E:3 (7) Expression.evaluate <class 'mathics.core.expression.Expression'>
         evaluate(MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 660, column 36
E:4 (10) Expression.rewrite_apply_eval_step.<locals>.eval_elements <class 'mathics.core.expression.Expression'>
          eval_elements() file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1270, column 17
E:5 (11) Expression.rewrite_apply_eval_step <class 'mathics.core.expression.Expression'>
          rewrite_apply_eval_step(Not[MatchQ[_, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]]],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 1284, column 13
E:6 (13) Expression.evaluate <class 'mathics.core.expression.Expression'>
          evaluate(Function[Not[MatchQ[#1, Alternatives[_ Blank, _ BlankSequence, _ BlankNullSequence]]]][_],
	)
     file '/tmp/Mathics3/mathics-core/mathics/core/expression.py' at line 660, column 36
(trepan3k) Leaving
trepan3k: That's all, folks...

Note that something inside Rubi is probably messing things up, because if you just run the usage definition:

In[1]:= Int::usage = "Int[expn, var] returns the antiderivative (indefinite integral) of <expn> with respect to <var>.\n" <>
In[2]:= ??Int
System`Information["Int", System`Rule[System`LongForm, System`True]]
Out[2]= Int[expn, var] returns the antiderivative (indefinite integral) of <expn> with respect to <var>.
        Int[{expn1, expn2, ...},var] returns a list of the antiderivatives of <expn1>, <expn2>, ... each with respect to <var>.
        Int[expn, {var, a, b}] returns the limit of the antiderivative of <expn> as <var> approaches <b> minus the limit as <var> approaches <a>. Note that this difference will NOT always equal the definite integral of <expn> from <a> to <b>.

[mmatera]

The infinite recursion happens at the level of one of the rules in DownValues[Int]: some condition that should not be evaluated. See for example:

In[1]:= Rubi.m;

and then

In[2]:= DownValues[Int][[1]]
Out[2]= HoldPattern[HoldPattern[HoldPattern[Int[Rubi`Private`u_. (Rubi`Private`A_. + Rubi`Private`B_. Rubi`Private`v_ + C_. Rubi`Private`v_ ^ 2) (Rubi`Private`a_ + Rubi`Private`b_. Rubi`Private`v_) ^ Rubi`Private`m_, x_Symbol]]]] ⧴ Rubi`Private`Simp[1 Int[Rubi`Private`u (Rubi`Private`a + Rubi`Private`b Rubi`Private`v) ^ (Rubi`Private`m + 1) Rubi`Private`Simp[Rubi`Private`b Rubi`Private`B - Rubi`Private`a C + Rubi`Private`b C Rubi`Private`v, x], x] / Rubi`Private`b ^ 2, x] /; FreeQ[{Rubi`Private`a, Rubi`Private`b, Rubi`Private`A, Rubi`Private`B, C}, x] ∧ Rubi`Private`EqQ[Rubi`Private`A Rubi`Private`b ^ 2 - Rubi`Private`a Rubi`Private`b Rubi`Private`B + Rubi`Private`a ^ 2 C, 0] ∧ Rubi`Private`LeQ[Rubi`Private`m, -1]


In[3]:= DownValues[Int][[1]]
In[3]:= DownValues[Int][[2]][[1]]
Out[3]= HoldPattern[HoldPattern[HoldPattern[Int[Rubi`Private`u_. (Rubi`Private`A_. + Rubi`Private`B_. Rubi`Private`v_ + C_. Rubi`Private`v_ ^ 2) (Rubi`Private`a_ + Rubi`Private`b_. Rubi`Private`v_) ^ Rubi`Private`m_, x_Symbol]]]]

In[4]:= DownValues[Int][[2]][[2]]
$RecursionLimit::reclim: Recursion depth of 200 exceeded.
Out[4]= $Aborted

In[5]:= DownValues[Int][[2]]//FullForm
Out[5]//FullForm= RuleDelayed[HoldPattern[HoldPattern[HoldPattern[Int[Times[Optional[Pattern[Rubi`Private`u, Blank[]]], Plus[Optional[Pattern[Rubi`Private`A, Blank[]]], Times[Optional[Pattern[Rubi`Private`B, Blank[]]], Pattern[Rubi`Private`v, Blank[]]], Times[Optional[Pattern[C, Blank[]]], Power[Pattern[Rubi`Private`v, Blank[]], 2]]], Power[Plus[Pattern[Rubi`Private`a, Blank[]], Times[Optional[Pattern[Rubi`Private`b, Blank[]]], Pattern[Rubi`Private`v, Blank[]]]], Pattern[Rubi`Private`m, Blank[]]]], Pattern[x, Blank[Symbol]]]]]], Condition[Rubi`Private`Simp[Star[Times[1, Power[Power[Rubi`Private`b, 2], -1]], Int[Times[Rubi`Private`u, Power[Plus[Rubi`Private`a, Times[Rubi`Private`b, Rubi`Private`v]], Plus[Rubi`Private`m, 1]], Rubi`Private`Simp[Plus[Times[Rubi`Private`b, Rubi`Private`B], Times[-1, Rubi`Private`a, C], Times[Rubi`Private`b, C, Rubi`Private`v]], x]], x]], x], And[FreeQ[{Rubi`Private`a, Rubi`Private`b, Rubi`Private`A, Rubi`Private`B, C}, x], Rubi`Private`EqQ[Plus[Times[Rubi`Private`A, Power[Rubi`Private`b, 2]], Times[-1, Rubi`Private`a, Rubi`Private`b, Rubi`Private`B], Times[Power[Rubi`Private`a, 2], C]], 0], Rubi`Private`LeQ[Rubi`Private`m, -1]]]]


In[6]:= DownValues[Int][[2,2,1]]//FullForm
$RecursionLimit::reclim: Recursion depth of 200 exceeded.
Out[6]= $Aborted

The rule, in a more readable form would be

HoldPattern[HoldPattern[HoldPattern[
    Int[(u_.)*((A_.) + (B_.)*(v_) + (C_.)*(v_)^2)*
      ((a_) + (b_.)*(v_))^
      (m_), x_Symbol]
       ]]] :> 
Condition[
	  Simp[1/b^2 ⋆ Int[u*(a + b*v)^(m + 1)*Simp[b*B - a*C + b*C*v, x], x], x],
	  (*condition:*)
	  FreeQ[{a, b, A, B, C},  x] && EqQ[A*b^2 - a*b*B + a^2*C, 0] && LeQ[m, -1]
]

The problem is that in Mathics, Condition is not HoldAll as in WMA, is HoldRest, so it tries to evaluate the first element, disregarding the condition. In WMA, at some point, for some evaluations, Condition is replaced by RuleCondition, which has the attribute HoldRest, but not when the rule is shown, but when the rule is applied.

[rocky]

So this is just a consequence of #1789, right?

[mmatera]

@rocky not sure about the causal relation, but they are clearly related.